Fabrication of electronic devices such as printheads for printing devices often includes the formation of a flexible polymer film at very precise tolerances. The completed film, for example a polyimide such as Kapton®, polyester, pressure-sensitive tapes, etc., can be used for various structures within an electronic device. For example, in an ink jet printhead, a thin film may be used along with other structures to channel ink through the printhead, or as an adhesive to bond adjacent printhead layers.
Mass producing a thin film having a uniform shape or geometry within tight tolerances is challenging, particularly for films having a thickness of one to two mils, or less. These thin films can easily stretch which distorts part geometries and can lead to scrap and increased costs. Securing a sheet of thin film material so that it remains stationary during cutting of several parts from the sheet can require complex tooling. Additionally, removal of waste material (slugs) can be difficult due to, for example, retention of the slugs by static electricity or adhesive that remains on the slugs or the part itself.
Various techniques are currently used to shape a thin film to desired dimensions. In one method, the sheet of thin film material is placed on top of a honeycomb panel and a vacuum is applied to the back side of the film. The film is then cut using, for example, a laser, mechanical blade, etc. As cutting occurs, the unwanted portions of the thin film and the slugs are extracted through the honeycomb panel, thereby uncovering and exposing the honeycomb panel. This exposure results in a reduction of the vacuum as material is cut away from the sheet, and a resulting decrease in the vacuum force applied to the back of the remaining film. As the vacuum applied to the remaining portion of the sheet tapers off, the sheet of thin film material can shift from its original position, and may be cut incorrectly. Thus the reduction in the vacuum force decreases the number of parts that may be cut at one time to ensure proper placement of the film during cutting.
Another method used to shape a thin film into a desired geometry includes the application of a pressure-sensitive adhesive tape to the sheet of thin film material. The pressure-sensitive adhesive tape secures the tape to the cutting fixture, and allows for processing of the thin film in the same way as that described above. In contrast to the use of a vacuum to secure the sheet, the adhesive secures the sheet of thin film material regardless of the number of sections that are cut and removed. However, during the removal of the thin film from the adhesive, the part may become deformed as a result of tensile forces placed on the part as the part is peeled from the adhesive during removal.
Yet another method used to shape a thin film includes a vacuum fixture and tooling having different manifolds for securing the part and extracting the slugs during sectioning of the thin film. The tooling may include relieved channels along the cutting path. While these fixtures may work well to provide properly shaped thin films, the fixture and tooling is extremely expensive and is custom for the shape and size of the part being produced. Design changes render the fixture obsolete and a new fixture must be designed and manufactured, which is expensive and may require large lead times.
A process for sectioning thin films into a desired shape within tight tolerances would be desirable.